Grapefruit, medicine interaction warning expanded

It has long been known that grapefruit juice can pose dangerous — and even deadly — risks when taken along with certain medications. Now, experts warn the list of medications that can result in these interactions is longer than many may have believed.

Check below to see whether your medication appears on the list.

In a new report released Monday in the Canadian Medical Association Journal, researchers at the University of Western Ontario said that while 17 drugs were identified in 2008 as having the potential to cause serious problems when taken with grapefruit, this number has now grown to 43.

“The frequency of these reactions may be small, but the risks are not worth it, especially for drugs which could cause sudden death,” said lead study author David Bailey, a professor of pharmacology and one of the first to report the interactions between grapefruit juice and certain medications 20 years ago. “Physicians need to know that this affects a number of new drugs and apply this information to their practice and patients.”

So how does a common breakfast fruit cause these problems? Grapefruits contain chemicals called furanocoumarins that interfere with how your body breaks down drugs before they enter the bloodstream. By preventing this normal breakdown of a drug, these chemicals in grapefruit can effectively cause a drug overdose and more severe side-effects.

Among the side effects sometimes seen with grapefruit-induced overdoses are heart rhythm problems, kidney failure, muscle breakdown, difficulty with breathing and blood clots. Atorvastatin — commonly known by the brand name Lipitor and taken by millions of Americans — is one of the drugs that have been linked to serious cases of drug toxicity when combined with grapefruit products. Other common heart medications — including verapamil and amiodarone — have also led to serious interactions when consumed with grapefruit or grapefruit juice.

While there have been many reported cases of serious side effects attributable to this problem, the total number of Americans who have been affected is not known.

As little as one grapefruit or one 8-ounce glass of grapefruit juice can cause an effect that may last more than 24 hours. Other fruits including Seville oranges, limes, and pomelos can have the same effect, although sweet orange varieties do not produce this interaction.

“People know that drugs react with drugs, but fewer are aware of drug-food interactions,” said Professor Paul Doering of the University of Florida Pharmacy Department. “Health professionals need to learn as much as they can about this. Undetected there are very serious adverse effects.”

For consumers, the best advice may be to ask a doctor or pharmacist when they are prescribed a new drug whether there are foods or other medicines that they should avoid.